1. Field of the Invention
The present invention relates to a circuit board containing a general-purpose region for mounting therein a general-purpose electrical part, a programmable region for mounting therein a programmable digital electrical part which are provided on the same board.
2. Description of Related Art
A print circuit board is used as a board for an electrical circuit. The print circuit board is formed by etching a wiring pattern of an electrical circuit which is designed in advance. For example, as the print circuit board are known a microcomputer mounting board which is installed in electrical equipment, an I/O board to be inserted into a blank slot of a computer, etc. Wires are formed as metal lines on these boards by etching, and thus it is difficult to change a connection pattern.
Further, as another electric circuit board is known a general-purpose board called as "universal board" which has holes formed in a grid pattern over the surface thereof. By using this board, wiring can be freely performed on a designed electric circuit even if it is any one of an analog circuit and a digital circuit. The pattern of this board can be relatively easily changed, however, mass production cannot be performed.
Still further, recently, great advances of semiconductor technologies enable high integration of transistors, and an electric part such as a programmable logic device which can program various circuits by using one chip is used for an electronic circuit. By using this device, the central circuit can be programmed. Therefore, the connection may be changed in the device without changing a wiring pattern of the print board, and the function thereof can be changed.
The print board on which a normal connection pattern is wired is suitable for mass production, however, it is difficult to change the circuit design. Further, the universal board has high degree of freedom in the circuit design. However, when an electronic circuit thus formed is required to be copied, the copied circuit may not be provided with the same circuit characteristic or wiring may fail because it is performed by a manual work. Accordingly, the electronic circuit using the universal board is unsuitable for the mass production.
Further, with respect to the general-purpose digital board on which a programmable logic device, etc. are mounted, the change of the function of the digital circuit and the change of the circuit can be easily performed by software, so that the failure of the manual work such as the failure of soldering due to these changes can be prevented. However, this board cannot be added with an analog circuit which is inherent to a user.
There is known a digital circuit board which is added with an analog circuit region in advance. However, in some cases the analog circuit cannot be operated well due to the effect of noises from the digital circuit. The analog circuit often needs plural power source voltages (for example, +5V, -5V) to operate, and it is difficult to supply plural power sources.
Further, a high-performance programmable logic device has a small pin interval, and thus it cannot use the conventional universal board which has 0.1-inch-interval holes. Therefore, when a programmable logic device is mounted, a novel board therefor must be provided every time.